5 rubber stamps cost $9.70. Which equation would help determine the cost of 11 rubber stamps?
Answer: There are several equations that could help determine the cost, each with a slightly different approach. If we let $x$ represent the cost of 11 rubber stamps, we have the following proportion: $\dfrac{x}{11}$ We have to pay $9.70 for 5 rubber stamps, and that can be written as a proportion: $\dfrac{\$9.70}{5}$ Since the price per rubber stamp stays the same, these two proportions are equivalent. $\dfrac{x}{11} = \dfrac{\$9.70}{5}$